Thirty-five years ago, this command might have been an incitement to something thrillingly delinquent. The legend is that one day in Key West around 1973, after evaporating his 20s with a monastic regimen of reading and writing that earned him the nickname "The White Knight," McGuane spotted a lissome gal on a bicycle pedaling by his front porch and simply wandered off in pursuit.

By the time five years had passed, he had imbibed a hallucinogen or two; sailed off on a few "carnal adventures," as he puts it; endured the end of two marriages (his first, of 10 years, to Becky Crockett, a direct descendant of Davy Crockett, and his second, lasting a mere six months, to Kidder); and, within a particularly rending 30 months, witnessed the deaths of both his parents and his sister.

He also did the novelist's standard stations-of-the-cross tour through Hollywood, a crawl ranging from the high of directing the film version of Ninety-two in the Shade to the low of being fired from Tom Horn by Steve McQueen. When it was all over, McGuane was overjoyed to return to the solitary freedom of his typewriter.

Of the '70s, McGuane has said that "everyone was in a slightly more festive mood." And of his passage through the better part of that decade, he says, "It's true that I've had a life that's, shall we say, wild. When I was in Hollywood, I took quite a lot of drugs, I drank an unnecessary amount.... People think you're going to die, and that excites them." He had simply wanted, "as the girls used to say in the romantic dramas, to live a little."

McGuane remembers going to a powwow on an Indian reservation with Harrison, with the two writers packing a full bottle of Jack Daniel's. They were stopped by two Indian policemen, who made them pour all the whiskey out onto the ground. "You would have seen four grown men crying," McGuane says with a laugh.

The turning point may have come in the late '70s, when he was living on a ranch in the Paradise Valley outside Livingston, Montana. McGuane stood at the center of a wild scene that included the writers William Hjorstberg, Richard Brautigan, and Tim Cahill; the actors Jeff Bridges and Peter Fonda (who would later marry McGuane's first wife); the painter Chatham; and the legendary director Sam Peckinpah.

Returning home from hunting one afternoon, he found the driveway crowded with pickups. His house in those days had become the group's hangout. "They were all around the kitchen table," McGuane says. "I was getting my stuff out of my truck, throwing it on the ground, and I got my rifle out, goddamn, and I fired it through my pickup truck just out of pique. All of a sudden people start running out, going, 'Bye, Tom, we're leaving.'"

By that point things had gotten so out of hand that McGuane fantasized about being thrown in prison. "That way I wouldn't want to run around or call girls up on the telephone," he says. Instead, McGuane quit drinking in 1981. "I didn't have the craving for alcohol," he says, "but I had very bad personality changes associated with it. And when I look around at my writer friends who are drinkers who get to be 70 or so – I mean, they are goners."

He mentions as a cautionary example the Montana writer James Crumley, who died at 68 in 2008. "He did cocaine six days a week," McGuane says. "Ate five times a day. Drank a bottle of whiskey every day. He said, 'This is how I like to live. If I live 10 years less, so what?' I couldn't live that way, couldn't do the things I like to do."

"Tom went through some pretty rough reality checks before he surfaced," Buffett says. "He was ahead of me on that learning curve, but not by much. I ask myself sometimes how we both made it through. A lot of characters from those days are dead."

This era receives its epitaph in Panama, an early survivor's note from the Me Decade that chronicles the consequences of near-terminal narcissism – including the possibility that no one may be home when you return from your epic trip of self-discovery.

On this bright morning, his head clear of anything stronger than carrot juice, McGuane saddles up to ride to the top of a mountain on the ranch to look for 50 or so cattle, a few of which need to be rounded up for a nearby cutting-horse competition next weekend. (Now ridden mostly in competition, cutting horses are specially trained to separate individual cows from a herd.)

"Anyone need more grease?" he asks, urging his fellow riders to lubricate themselves with sunscreen.